The present invention relates to grinding machines or analogous machine tools in general, and more particularly to improvements in grinding machines of the type wherein one or more units (such as the headstock or the tailstock for the workpiece, a dressing tool or a measuring device) must be adjusted with reference to the work supporting table when the machine tool is to be converted from the treatment of a first batch of workpieces to the treatment of a second batch of different workpieces. The invention also relates to a method of converting a grinding machine or an analogous machine tool for the treatment of different types of workpieces.
It is customary to provide the work supporting table of a plain or rotary grinding machine with a first work supporting unit (e.g., a headstock) and a second work supporting unit (e.g., a tailstock). Each of these units comprises or can comprise a center for the respective axial end of a rotatable workpiece and one of the units is normally provided with a drive which rotates the workpiece during removal of material therefrom by one or more driven grinding wheels or analogous material removing tools. The table can also carry other types of work supporting units, e.g., one or more steady rests or the like. Furthermore, the table can carry one or more distance measuring devices (e.g., diameter measuring or monitoring gauges, gauges which are designed to monitor the distance between a shoulder on the workpiece and the grinding station and/or others). Still further, the table can support a dressing apparatus for the grinding wheel or wheels. All or at least some of these units must be adjusted with reference to the table before the machine is ready to proceed with the treatment of a fresh set of workpieces whose dimensions deviate from those of the previously treated workpieces. For example, it is necessary to shift at least one of the work supporting units relative to the table when the grinding machine is to treat a fresh series of workpieces which are longer or shorter than the previously treated workpieces. This will be readily appreciated by bearing in mind that each workpiece is normally held between a pair of centers and that the distance between the centers must be changed if a relatively short workpiece is to be followed by a relatively long workpiece or vice versa. As a rule, it is the headstock or the tailstock which must be shifted relative to the work supporting table before the grinding machine is ready to treat a series of different workpieces. Furthermore, it is often necessary to change the position or positions of one or more steady rests if the machine is equipped with such units.
If the grinding machine is a numerically controlled machine tool, it is evidently desirable and advantageous to carry out any and all changes of the setup in a fully automatic way, i.e., in response to signals from the controls of the machine. It is already known to provide a discrete drive for a unit which must be adjusted with reference to the work supporting table of the grinding machine before the latter is ready to treat a different set of workpieces, and to automatically actuate such drive in response to signals from the numerical control means. As a rule, a discrete drive is provided only for that unit or for those units which require frequent adjustments with reference to the table, particularly for the headstock or tailstock on the table. The provision of one or more discrete drives, operative connections between such drive or drives and the respective unit or units on the table, and operative connections between such drive or drives and the controls of the machine contributes significantly to the bulk, initial cost and maintenance cost of the machine. Moreover, each adjustable unit is normally associated with a position monitoring device whose location relative to the table must be changed whenever the position of the corresponding unit is changed. This is the reason that, as a rule, presently known grinding machines are provided with a numerically controlled drive for only one of the units which must be adjusted with reference to the work supporting table before the machine is ready to treat a different set of workpieces. All other units are adjusted by hand which is a time-consuming operation and adversely affects the output of the machine.
Another drawback of presently known grinding machines and analogous machine tools of the above outlined character is that the drive or drives for one or more adjustable units cannot be readily installed in or on existing machines. In fact, even the incorporation of such features in presently known types of grinding machines during the making and assembly of such machines presents serious problems and unduly increases their initial cost because the drives and their connections to the respective units and to the controls occupy too much space which is not readily available in presently known types of grinding and like machines.